diff --git a/gcc/config/mips/mips.c b/gcc/config/mips/mips.c
index b6a2290..820b228 100644
--- a/gcc/config/mips/mips.c
+++ b/gcc/config/mips/mips.c
@@ -16757,6 +16757,9 @@ mips_option_override (void)
   for (i = FP_REG_FIRST; i <= FP_REG_LAST; i++)
     mips_dbx_regno[i] = i + start;
 
+  for (i = ALL_COP_REG_FIRST; i <= ALL_COP_REG_LAST; i++)
+    mips_dbx_regno[i] = IGNORED_DWARF_REGNUM;
+
   /* Accumulator debug registers use big-endian ordering.  */
   mips_dbx_regno[HI_REGNUM] = MD_DBX_FIRST + 0;
   mips_dbx_regno[LO_REGNUM] = MD_DBX_FIRST + 1;
diff --git a/gcc/config/mips/mips.h b/gcc/config/mips/mips.h
index 308b59b..60b26cb 100644
--- a/gcc/config/mips/mips.h
+++ b/gcc/config/mips/mips.h
@@ -1641,8 +1641,11 @@ struct mips_cpu_info {
 #define COP3_REG_FIRST 144
 #define COP3_REG_LAST 175
 #define COP3_REG_NUM (COP3_REG_LAST - COP3_REG_FIRST + 1)
-/* ALL_COP_REG_NUM assumes that COP0,2,and 3 are numbered consecutively.  */
-#define ALL_COP_REG_NUM (COP3_REG_LAST - COP0_REG_FIRST + 1)
+
+/* These definitions assume that COP0, 2 and 3 are numbered consecutively.  */
+#define ALL_COP_REG_FIRST COP0_REG_FIRST
+#define ALL_COP_REG_LAST COP3_REG_LAST
+#define ALL_COP_REG_NUM (ALL_COP_REG_LAST - ALL_COP_REG_FIRST + 1)
 
 #define DSP_ACC_REG_FIRST 176
 #define DSP_ACC_REG_LAST 181
diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index f0256ae..c92fa4b 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -10499,7 +10499,12 @@ reg_loc_descriptor (rtx rtl, enum var_init_status initialized)
   if (hard_regno_nregs[REGNO (rtl)][GET_MODE (rtl)] > 1 || regs)
     return multiple_reg_loc_descriptor (rtl, regs, initialized);
   else
-    return one_reg_loc_descriptor (dbx_reg_number (rtl), initialized);
+    {
+      unsigned int dbx_regnum = dbx_reg_number (rtl);
+      if (dbx_regnum == IGNORED_DWARF_REGNUM)
+	return 0;
+      return one_reg_loc_descriptor (dbx_regnum, initialized);
+    }
 }
 
 /* Return a location descriptor that designates a machine register for
@@ -11926,6 +11931,7 @@ mem_loc_descriptor (rtx rtl, enum machine_mode mode,
 	      ))
 	{
 	  dw_die_ref type_die;
+	  unsigned int dbx_regnum;
 
 	  if (dwarf_strict)
 	    break;
@@ -11935,8 +11941,12 @@ mem_loc_descriptor (rtx rtl, enum machine_mode mode,
 					 GET_MODE_CLASS (mode) == MODE_INT);
 	  if (type_die == NULL)
 	    break;
+
+	  dbx_regnum = dbx_reg_number (rtl);
+	  if (dbx_regnum == IGNORED_DWARF_REGNUM)
+	    break;
 	  mem_loc_result = new_loc_descr (DW_OP_GNU_regval_type,
-					  dbx_reg_number (rtl), 0);
+					  dbx_regnum, 0);
 	  mem_loc_result->dw_loc_oprnd2.val_class = dw_val_class_die_ref;
 	  mem_loc_result->dw_loc_oprnd2.v.val_die_ref.die = type_die;
 	  mem_loc_result->dw_loc_oprnd2.v.val_die_ref.external = 0;
@@ -12138,9 +12148,13 @@ mem_loc_descriptor (rtx rtl, enum machine_mode mode,
 	    op0 = mem_loc_descriptor (ENTRY_VALUE_EXP (rtl), mode,
 				      VOIDmode, VAR_INIT_STATUS_INITIALIZED);
 	  else
-	    op0
-	      = one_reg_loc_descriptor (dbx_reg_number (ENTRY_VALUE_EXP (rtl)),
-					VAR_INIT_STATUS_INITIALIZED);
+	    {
+              unsigned int dbx_regnum = dbx_reg_number (ENTRY_VALUE_EXP (rtl));
+	      if (dbx_regnum == IGNORED_DWARF_REGNUM)
+		return NULL;
+	      op0 = one_reg_loc_descriptor (dbx_regnum,
+					    VAR_INIT_STATUS_INITIALIZED);
+	    }
 	}
       else if (MEM_P (ENTRY_VALUE_EXP (rtl))
 	       && REG_P (XEXP (ENTRY_VALUE_EXP (rtl), 0)))
diff --git a/gcc/rtl.h b/gcc/rtl.h
index a0fb4f7..5b9ceb8 100644
--- a/gcc/rtl.h
+++ b/gcc/rtl.h
@@ -2439,6 +2439,9 @@ extern rtx gen_rtx_MEM (enum machine_mode, rtx);
 /* REGNUM never really appearing in the INSN stream.  */
 #define INVALID_REGNUM			(~(unsigned int) 0)
 
+/* REGNUM for which no debug information can be generated.  */
+#define IGNORED_DWARF_REGNUM            (INVALID_REGNUM - 1)
+
 extern rtx output_constant_def (tree, int);
 extern rtx lookup_constant_def (tree);